Getting Depths of Images

I frequently get asked, "how deep was that?" when people see my images, and I've often wanted to have that information too. I finally took it upon myself to build a system for retrieving the depth at which an image was taken, and adding it to the data about an image.

I bought a SensusPro (http://www.reefnet.ca/), which is basically a small depth/time/temperature logging device. It is about the size of a book of matches (a little thicker), and can be read from windows, linux. palm, and a Mac (I'm a Mac and Linux guy myself). The SensusPro uses the time on the computer to which it's connected to figure out what time the dive started, ended, etc. It takes readings once a second during the entire dive, and can store about 10 hours of diving. You can adjust the interval to store more dive time if you like. With this I have a very fine-grained record of depths for my entire dive.

If I keep my camera timestamps synced up with my laptop (I have Canon DSLRs) by connecting it up, and setting the camera time from the computer, now my records of my dives, and my timestamps on my images are fairly close to the same (say within a second or so).

I've got some software I hacked together that can take a given image, read the timestamp out of the exif data, and match it up with a timestamp in my dive records, and give me the depth and temperature when I took that image. If it doesn't find an exact match, it goes through and finds the closest timestamp, and uses that.

So now I can go through and shoot an entire trip, not worrying about trying to remember anything, and later I can put my code to work figuring out the depths and times. I've even been able to build little graphs of my dive profile that has dots where images where taken on that particular dive.

Don't know if other folks out there have the same need, but it can be done, and it works really well.

Cheers,

Jon

http://www.jongrossphotography.com

Hi!

There's a position tag (lat., long., alt.) in the EXIF data where you might store the depth info!

Helge ;-)=)

Hi!

 

There's a position tag (lat., long., alt.) in the EXIF data where you might store the depth info!

 

Helge ;-)=)

I can't seem to find that EXIF tag in the Canon EXIF data. Is it an IPTC standard field? Right now I'm sort of working on getting all my tags into XMP files, since the Photoshop gorilla seems to be headed that way...

--

http://www.jongrossphotography.com

Hi!

I had a quick look at the EXIF spec. GPS data is a standard tag. The altitude value is usually regarded relative to sea level so it isn't really meant for keeping the depth but I think there are worse places to keep it.

There's also a geo-info tag that keeps lat, long, alt tags. I haven't got an in-depth knowledge of the EXIF format (yet) so it's up to you to find out the details.

What I've got is a link to some further information (referencing these tags too).

http://www.w3.org/2003/12/exif

http://home.arcor.de/ahuggel/exiv2/tags.html

The fields may be ommitted in your camera but writing them later on should work. Be careful not to break manufacturer specific tags.

Helge ;-)=)

so how deep were you ?

so how deep were you ?

about 5 foot down the html document ;-) That's EXIF snorkelling only ...

Helge ;-)=)

Lol, everyone to his own, and we all have our preferences. Personally, the only time I would ever want to remember my depth when taking pics is when i want to return for more pics i.e. Pygmy Seahorses ....... shot a role on P. Seahorse in manado and on the ascent ( ooppsss incurred deco aswell ) i noticed that i forgot to turn on the strobes... and with Velvia fim, we alll know what that means. Luckily i did know the depth, so finding them then next day was easy.

Hi!

You need the depth for scientific purposes. Medslugs e.g. ask for depth info to get additional data on the nudies.

Helge ;-)=)

Hi!

 

You need the depth for scientific purposes. Medslugs e.g. ask for depth info to get additional data on the nudies.

 

Helge ;-)=)

In addition, I believe that images that many of us take can serve an important record of what used to be where. I know that sounds gloomy, but I really try to keep a complete record of what I find, where, under what conditions. You never know when that sort of information will come in handy. It might not be important to me, but like Helge mentioned above, it's hard to have too specific a data set for scientific inquiry...

jon

http://www.jongrossphotography.com

Personally, my diving computer (Cobra) let's me make a tag everytime I want to by just pressing a button. So when I know I need a reference, I take the picture(s) and make a tag in my dive log. When I go back to my computer I have all the info I need (depth, time, etc.).

Peace,

David.

Hi!

my diving computer (Cobra) let's me make a tag everytime I want to by just pressing a button

Mine too (I'm currently test diving an Uwatec Tec). But what I'd end up would be a complete mess of markers along the profile. Usually I'll do at least about 60-80 pictures per dive. That's an average of one picture per minute. I need the data just for a couple of images (the others are kept as a backup only).

With an outcome rate of sometimes 1:20 (I don't show every image I take out of self critisism) it'd be too much effort of bookmarking every shot during the dive. What I do is looking up the images in question manually in the profiles. That's why I find the automated tagging in the EXIF so appealing. Either from a dedicated device or from the computer profile. After running the batch you've got the info where it belongs to, in the image.

Helge ;-)=)

The D1x can hook up to a gps devise and record the position in the exif in camera. I would think that it would be easy for housing manufacutres the stick a depth gauge on the side of the housing and have it plug into the gps slot. This way the files coming out of the camera would allready have depth info in them. If only more cameras had this ability.

Hi!

It's quite easy with the D1x. You have to transfer the position as NMEA record via a serial connection. All you need would be a depth sensor and a small single chip CPU to do a bit math and to transfer the data. It's a pity that this is the only camera supporting location info. No more questions like "where did I take this picture?" ;-)

Helge ;-)=)